Originally Posted by
AJA_
I always refer to the lounge guide on the oneworld website
https://www.oneworld.com/airport-lounges
It notes specific exclusions for Qatar Airways Privelege Club, American Airlines AAdvantage and SriLankan Flysmiles members and lists specific exclusions at the particular airport but in general OW Sapphire status gives you access to any OW biz lounge regardless of cabin flown provided you are flying on a OW airline.
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This information may not be up to date - I came out of Doha on a BA J ticket two weeks ago and used the AL-Mourjan lounge (it was even printed on my boarding pass) - and so did my wife travelling a few days later.